Radio frequency generators, and related systems, methods, and devices

ABSTRACT

One or more example relate, generally, to generating radio frequency (RF) signals. An apparatus may include a signal generator, an amplification stage, and a feedback control loop. The signal generator may generate a pulsed radio frequency (RF) signal at least partially responsive to a digital pulsed waveform defined by one or more commands. The amplification stage may amplify the pulsed RF signal. The feedback control loop may be coupled to the amplification stage to regulate a power level of respective steps of the pulsed RF signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/731,578, filed Dec. 31, 2019, which will issue as U.S. Pat. No.11,587,767 on Feb. 21, 2023, which claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application Ser. No. 62/863756, filedJun. 19, 2019, and U.S. Provisional Patent Application Ser. No.62/872142, filed Jul. 9, 2019, the disclosures of each are herebyincorporated herein in its entirety by this reference.

FIELD

The present disclosure relates generally to radio frequency (RF) signalgeneration, and more specifically, to generating a pulsed RF signalhaving an envelope of arbitrary, multi-step, or single-step pulses ofany shape, yet further embodiments relate to RF plasma generation usingsuch pulsed RF signals.

BACKGROUND

In a plasma semiconductor manufacturing processes, a radio frequency(RF) generator is used in capacitively or inductively coupled plasmageneration as an RF excitation source as part of the plasmasemiconductor manufacturing process. A pulsed RF signal is typicallyused in a plasma semiconductor manufacturing process to control etchand/or deposition profiles. Typically, performing pulsed RF in a plasmasemiconductor manufacturing processes involves feeding pulses created byan external pulsed signal generator via an external connector (Pulse_In)to the RF generator. The signal generator is typically a stand-alonepiece of equipment, and it has limited waveform options. Anotherstandard pulsing technique may include on/off, single step RF pulsingthat is created internal to the RF the generator.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a block diagram of an example RF generation system, inaccordance with a number of embodiments of the present disclosure.

FIG. 1B is a block diagram of another example RF generation system, inaccordance with a number of embodiments of the present disclosure.

FIG. 2A is a block diagram of another example RF generation system,according to a number of embodiments of the present disclosure.

FIG. 2B is a block diagram of another example RF generation system, inaccordance with a number of embodiments of the present disclosure.

FIG. 3A is a block diagram of another example RF generation system,according to a number of embodiments of the present disclosure.

FIG. 3B is a block diagram of yet another example RF generation system,according to a number of embodiments of the present disclosure.

FIG. 4 depicts an example semiconductor manufacturing system, inaccordance with one or more embodiments of the present disclosure.

FIG. 5 depicts an example RF plasma generator, according to one or moreembodiments of the present disclosure.

FIGS. 6A-6F depict waveforms comprising pulse trains having variousnon-limiting examples of pulse waveforms, in accordance with variousembodiments of the present disclosure.

FIG. 7 is a flowchart of an example method of generating a pulsed RFsignal, in accordance with various embodiments of the presentdisclosure.

DETAILED DESCRIPTION

The illustrations presented herein are not meant to be actual views ofany particular method, system, device, or structure, but are merelyidealized representations that are employed to describe the embodimentsof the present disclosure. The drawings presented herein are notnecessarily drawn to scale. Similar structures or components in thevarious drawings may retain the same or similar numbering for theconvenience of the reader; however, the similarity in numbering does notmean that the structures or components are necessarily identical insize, composition, configuration, or any other property.

The following description may include examples to help enable one ofordinary skill in the art to practice the disclosed embodiments. The useof the terms “exemplary,” “by example,” and “for example,” means thatthe related description is explanatory, and though the scope of thedisclosure is intended to encompass the examples and legal equivalents,the use of such terms is not intended to limit the scope of anembodiment or this disclosure to the specified components, steps,features, functions, or the like.

It will be readily understood that the components of the embodiments asgenerally described herein and illustrated in the drawing could bearranged and designed in a wide variety of different configurations.Thus, the following description of various embodiments is not intendedto limit the scope of the present disclosure, but is merelyrepresentative of various embodiments. While the various aspects of theembodiments may be presented in drawings, the drawings are notnecessarily drawn to scale unless specifically indicated.

Furthermore, specific implementations shown and described are onlyexamples and should not be construed as the only way to implement thepresent disclosure unless specified otherwise herein. Elements,circuits, and functions may be shown in block diagram form in order notto obscure the present disclosure in unnecessary detail. Conversely,specific implementations shown and described are exemplary only andshould not be construed as the only way to implement the presentdisclosure unless specified otherwise herein. Additionally, blockdefinitions and partitioning of logic between various blocks isexemplary of a specific implementation. It will be readily apparent toone of ordinary skill in the art that the present disclosure may bepracticed by numerous other partitioning solutions. For the most part,details concerning timing considerations and the like have been omittedwhere such details are not necessary to obtain a complete understandingof the present disclosure and are within the abilities of persons ofordinary skill in the relevant art.

Those of ordinary skill in the art would understand that information andsignals may be represented using any of a variety of differenttechnologies and techniques. Some drawings may illustrate signals as asingle signal for clarity of presentation and description. It will beunderstood by a person of ordinary skill in the art that the signal mayrepresent a bus of signals, wherein the bus may have a variety of bitwidths and the present disclosure may be implemented on any number ofdata signals including a single data signal.

The various illustrative logical blocks, modules, and circuits describedin connection with the embodiments disclosed herein may be implementedor performed with a general purpose processor, a special purposeprocessor, a Digital Signal Processor (DSP), an Integrated Circuit (IC),an Application Specific Integrated Circuit (ASIC), a Field ProgrammableGate Array (FPGA) or other programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof designed to perform the functions described herein. Ageneral-purpose processor (may also be referred to herein as a hostprocessor or simply a host) may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, such as a combinationof a DSP, FPGA and a microprocessor, a plurality of microprocessors, oneor more microprocessors in conjunction with a DSP core, or any othersuch configuration. A general-purpose computer including a processor isconsidered a special-purpose computer while the general-purpose computeris configured to execute computing instructions (e.g., software code)related to embodiments of the present disclosure.

The embodiments may be described in terms of a process that is depictedas a flowchart, a flow diagram, a structure diagram, or a block diagram.Although a flowchart may describe operational acts as a sequentialprocess, many of these acts can be performed in another sequence, inparallel, or substantially concurrently. In addition, the order of theacts may be re-arranged. A process may correspond to a method, a thread,a function, a procedure, a subroutine, a subprogram, etc. Furthermore,the methods disclosed herein may be implemented in hardware, software,or both. If implemented in software, the functions may be stored ortransmitted as one or more instructions or code on computer-readablemedia. Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another.

Any reference to an element herein using a designation such as “first,”“second,” and so forth does not limit the quantity or order of thoseelements, unless such limitation is explicitly stated. Rather, thesedesignations may be used herein as a convenient method of distinguishingbetween two or more elements or instances of an element. Thus, areference to first and second elements does not mean that only twoelements may be employed there or that the first element must precedethe second element in some manner. In addition, unless stated otherwise,a set of elements may comprise one or more elements.

As used herein, the term “substantially” in reference to a givenparameter, property, or condition means and includes to a degree thatone of ordinary skill in the art would understand that the givenparameter, property, or condition is met with a small degree ofvariance, such as, for example, within acceptable manufacturingtolerances. By way of example, depending on the particular parameter,property, or condition that is substantially met, the parameter,property, or condition may be at least 90% met, at least 95% met, oreven at least 99% met.

As used herein “arbitrary waveform” and “arbitrary shape” each mean thatthe waveform or shape, as the case may be, is a user defined shape.

Some embodiments relate, generally, to an RF generator that isconfigured to modulate, or pulse, an RF signal using a pulsing waveform(i.e., the modulating signal) and output a pulsed RF signal. Accordingto various embodiments, an envelope of the pulse RF signal may followthe modulating signal waveform. In at least one embodiment, the RFgenerator is configured to modulate/pulse an RF carrier using amodulating signal having an arbitrary waveform. An arbitrary pulsingwaveform may comprise one or more types of pulses, wherein each pulsemay have an N-step shape, arbitrary shape, or any other shape. Asnon-limiting examples, a shape of a pulse may be arbitrary in terms ofnumber of steps, ramp up and down periods, pulse width, amplitude, arandom shape, or any combination thereof. As further non-limitingexamples, a pulsed waveform may be arbitrary because a waveform of afirst pulse period and a waveform of a second pulse period havedifferent shapes.

Further, some embodiments relate, generally, to a pulsed RF generatorthat is configured to receive and/or store one or more pulse waveforms,and generate a pulsed analog RF signal having the envelope of the pulsewaveform. In one embodiment, a pulsing (RF modulating) waveform may begenerated at a computer (e.g., using simulation software such as MATLABor MS Excel, without limitation,) and a waveform file may be loadedonto, and possibly stored on, the RF generator for use by the RFgenerator to generate a pulsed output RF signal. It will be appreciatedthat for such embodiments, a user may create pulsed waveforms havingmulti-step, single-step, arbitrary, or any other shape for use by the RFgenerator to pulse the generator RF output. In embodiments where the RFgenerator is configured to store multiple pulsed waveforms, the pulsingwaveforms may be selectable by a user using an interface and/or acomputer operatively coupled to the RF generator by a data port. Inother words, a user may select a waveform to use to generate a pulsed RFanalog signal for use as a modulating signal. It will be appreciatedthat for such embodiments, a user is not limited to using a single orjust a few pulsed waveforms with an RF generator, but many.

As a non-limiting example of a contemplated use case, a manufacturer ofsemiconductor manufacturing equipment that includes one or moreembodiments of pulsed RF generators disclosed herein may create anarbitrary pulsed waveform (e.g., a single-period of an arbitrary pulsedwaveform) on a computer. The semiconductor manufacturer may load thepulsing waveform onto the RF generator through, for example, aninterface of the RF generator. In some embodiments, the interface is aninterface board with data bus, memory, and/or a microprocessor, withoutlimitation. As non-limiting examples, the interface board may use anRS232 serial interface, an analog interface, a deviceNet interface,profibus interface, CAN open interface, EtherCAT, an Ethernet Interface,or a custom interface, without limitation, to communicate with thecomputer. The RF generator may read the single-period arbitrary pulsingwaveform via the interface, and use the single-period to stitch acontinuous arbitrary pulsed waveform that may be used to generate amodulating signal for modulating an RF signal to create an arbitrarypulsed RF signal (e.g., a pulsed RF signal with an arbitrary waveform).

In some embodiments, a stored pulsed waveform may include power levelinformation at each waveform point. In these embodiments, during acontemplated operation, a digital or analog controlled feedback loop ofa power generator may use the stored power level information to regulatea power level of a generated pulsed RF signal. In disclosed embodiments,any suitable digital or analog controlled feedback loop may be used,such as, for example, a digital proportional-integral-derivative (PID)controller or an analog PID controller, without limitation.

Various embodiments may provide for precise control of peak power ateach pulse step, in single, multi-step, or arbitrary pulsed RF output.Having the ability to regulate the power level at each step (e.g., witha complicated PID controller that controls the set point at each step)is unique.

In some embodiments, a single-period pulsed waveform may be obtained bystitching together two or more stored single-period pulsed waveforms. Inone use case, when selecting a stored pulsed waveform to use for pulseRF signal generation, a user may select two or more stored waveforms,and select the combination of the two or more waveforms, or select partsof the waveforms and select the combination of the parts of thewaveforms, and obtain a pulsed RF waveform that is the combination ofthe two or more waveforms.

As described more fully below, according to some embodiments (e.g., suchas the embodiments of FIGS. 1A, 2A, and 3A), a mixer may be used tomodulate a RF signal. In other embodiments (e.g., such as theembodiments of FIGS. 1B, 2B, and 3B), a power set point may be used tomodulate a RF signal.

FIG. 1A depicts an example RF generation system 100, in accordance withdisclosed embodiments. RF generation system 100 includes an RF generator102 configured to receive and/or store waveforms for generating a pulsedRF signal. RF generation system 100 further includes a computer 104 anda waveform file 106.

RF generator 102 includes an interface 108, a digital shaper 110, adigital-to-analog (D/A) converter 112, a mixer 114, a pre-amplifier 115,and a filter 116. RF generator 102 further includes an automatic gaincontrol (AGC) amplifier 118, a power amplifier 120, a power sensor 122,and a control unit 124. In some embodiments, RF generator includes afeedback loop 126. Further, AGC amplifier 118 and/or power amplifier 120may be part of an amplification stage.

In a contemplated operation, a user may create an arbitrary pulsedwaveform (e.g., via computer 104), and waveform file 106 for thearbitrary pulsed waveform may be provided to from computer 104 to RFgenerator 102 via interface 108. A digital representation of thearbitrary pulsed waveform may be received at digital shaper 110, whichis configured to stitch the single-period waveform into a continuouspulsed waveform and output a digital stream representative of thecontinuous pulsed waveform. D/A converter 112 generates an analog signalhaving the pulsed waveform in response to the digital continuous pulsedwaveform received from digital shaper 110. The analog signal is conveyedto mixer 114. Further, a RF signal (e.g., RF carrier signal), generatedvia, for example, a direct digital synthesizer (DDS) or a crystaloscillator, is received at pre-amplifier 115 and conveyed to mixer 114.

Mixer 114 modulates the RF signal using the analog signal as amodulating signal to generate a pulsed RF signal, which is filtered viafilter 116. Further, AGC amplifier 118 attenuates a power level of thepulsed RF signal in response to an error signal generated by viafeedback loop 126. Power amplifier 120 amplifies the attenuated pulsedRF signal and outputs an amplified pulsed RF signal. Power sensor 122samples the amplified pulsed RF signal at some sampling frequency, andoutputs the amplified pulsed RF signal (“Pulsed RF Out”). Samples of theamplified RF signal may be conveyed from power sensor 122 to controlunit 124. Power sensor 122 may be any suitable power sensor for RFgeneration applications, including, as non-limiting examples, adirectional coupler that takes power samples, or a voltage/current (V/I)sensor that takes voltage samples, and current samples, or anycombination thereof, without limitation. In some embodiments, acalibration table may be included (e.g., between power sensor 122 andcontrol unit 124; not shown). In some embodiments, feedback loop 126compares pre-defined set points (e.g., at control unit 124) to thesamples (e.g., after being converted to power or V/I using look up orcalibration tables) and generates an error signal indicative of adifference between the power samples and the set points. It is notedthat a set point within control unit 124 may be modified to achievepower regulation at different steps.

In some embodiments, AGC amplifier 118 may change the attenuationapplied to the power level of the pulsed RF in response to changes tothe error signal to regulate power. A PID or any feedback controller(e.g., within feedback loop 126 (e.g., control unit 124)) may modify theset point for each pulse step or arbitrary wave form to regulate peakpower and for precise power control at each pulsed RF step or level.

FIG. 1B depicts another example RF generation system 150, in accordancewith disclosed embodiments. RF generation system 150 includes an RFgenerator 152 and a computer 154. RF generator 152 includes a waveformfile 156, an interface 158, a digital shaper 160, and adigital-to-analog (D/A) converter 162. RF generator 152 further includesa pre-amplifier 165, a filter 166, an AGC amplifier 168, a poweramplifier 170, a power sensor 172, and a control unit 174. In someembodiments, RF generator 152 includes a feedback loop 176. Further, AGCamplifier 168 and/or power amplifier 170 may be part of an amplificationstage.

In a contemplated operation of RF generation system 150, waveform file156, which may exist on RF generator 152, may be provided to digitalshaper 160 via interface 158. For example, a digital representation ofthe arbitrary pulsed waveform (e.g., of waveform file 156) may bereceived at digital shaper 160, which is configured to stitch thesingle-period waveform into a continuous pulsed waveform and output adigital stream representative of the continuous pulsed waveform. D/Aconverter 162 may generate an analog signal having the pulsed waveformin response to the digital continuous pulsed waveform received fromdigital shaper 160. The analog signal may be received at control unit174, which may convey the analog signal to AGC amplifier 268.

A RF signal (e.g., RF carrier signal), generated via, for example, adirect digital synthesizer (DDS) or a crystal oscillator, is received atpre-amplifier 165 and conveyed to AGC amplifier 168. In response to theRF signal, AGC amplifier 168 generates a pulsed RF signal, which isfiltered via filter 166.

AGC amplifier 168 may attenuate a power level of the pulsed RF signal inresponse to an error signal generated by via feedback loop 176. Poweramplifier 170 amplifies the attenuated pulsed RF signal and outputs anamplified pulsed RF signal. Power sensor 172, samples the amplifiedpulsed RF signal at some sampling frequency, and outputs the amplifiedpulsed RF signal (“Pulsed RF Out”). Samples of the amplified RF signalmay be conveyed from power sensor 172 to control unit 174. Power sensor172 may be any suitable power sensor for RF generation applications,including, as non-limiting examples, a directional coupler that takespower samples, or a voltage/current (V/I) sensor that takes voltagesamples, and current samples, or any combination thereof, withoutlimitation. In some embodiments, a calibration table may be included(e.g., between power sensor 172 and control unit 174; not shown).Feedback loop 176 compares pre-defined set points (e.g., at control unit174) to the samples (e.g., after being converted to power or V/I usinglook up or calibration tables) and generates an error signal indicativeof a difference between the power samples and the set points. It isnoted that the set point within control unit 174 may be modified toachieve power regulation at different steps.

In some embodiments, AGC amplifier 168 may change the attenuationapplied to the power level of the pulsed RF in response to changes tothe error signal to regulate power. A PID or any feedback controller(e.g., within feedback loop 176 (e.g., control unit 174)) may modify theset point for each pulse step or arbitrary wave form to regulate peakpower and for precise power control at each pulsed RF step or level.

Some embodiments relate, generally, to a pulse generation system where auser may create a pulsed analog signal of arbitrary, multi-step, orsingle-step pulses of any shape, and provide the pulsed/modulatinganalog signal directly to an RF generator. The RF generator may use thepulsed analog signal as a modulating signal for modulating an RF carrierand to generate a pulsed RF signal. In various disclosed embodiments,when creating a pulsed signal, a user may control for various pulsecharacteristics. Non-limiting examples of pulse characteristics includeduty cycle, pulse repetition frequency, rise and fall times, andcombinations thereof, without limitation. In some embodiments, the usercreates a number (e.g., a series) of commands for describing a pulsedwaveform having specific pulse characteristics using a syntax recognizedby the RF generator. In some embodiments, the RF generator is configuredto interpret the commands to create a pulsed signal having a waveformthat results from following the commands according to a pre-definedschema. In some embodiments, the RF generator is configured to store thecommands, a waveform file defining a single-period of the pulsed analogsignal, and/or a digital representation of a single-period of the pulsedanalog signal.

In some embodiments, the commands sent to the RF generator may includepower level information at each waveform point. In a contemplatedoperation, a digital or analog controlled feedback loop of a powergenerator may use the stored power level information to regulate a powerlevel of a generated pulsed RF signal. In disclosed embodiments, anysuitable digital or analog controlled feedback loop (e.g., including thefeedback loops shown in FIGS. 1A and 1B) may include, for example, adigital proportional-integral-derivative (PID) controller or an analogPID controller, without limitation.

FIG. 2A shows an embodiment of an example RF generation system 200including an RF generator 202, according to various embodiments of thedisclosure. RF generation system 200 further includes a computer 204 andcommands 206, which may include a series (e.g., one or more) ofcommands. For example, commands 206 may include commands for describinga pulsed waveform having specific pulse characteristics using a syntaxrecognized by RF generator 202.

RF generator 202 includes an interface 208, a digital shaper 210, adigital-to-analog (D/A) converter 212, a mixer 214, a pre-amplifier 215,and a filter 216. RF generator 202 further includes an AGC amplifier218, a power amplifier 220, a power sensor 222, and a control block 224.In some embodiments, RF generator 202 includes a feedback loop 226.Further, AGC amplifier 218 and/or power amplifier 220 may be part of anamplification stage.

In some embodiments, computer 204 is used to generate commands 206 thatuse a syntax for describing pulse characteristics of a pulsed waveform.Commands 206 may be provided to RF generator 202 via interface (e.g., aninterface similar to the interface described with reference to FIGS. 1Aand 1B) 208. For example, commands 206 may include power levels and timespan for each segment in the pulse span. Commands 206 are received atdigital shaper 210, which is configured to interpret the commands togenerate a digital representation of a single-period pulsed waveform andto stich the single-period of the pulsed waveform into a continuouspulsed waveform. Digital shaper 210 outputs a bit stream representativeof the digital pulsed waveform. D/A converter 212 generates an analogpulsed signal in response to the digital continuous pulsed waveformreceived from digital shaper 210. The analog pulsed signal may bereceived at mixer 214.

A RF signal (e.g., an RF carrier signal), generated via, for example, adirect digital synthesizer (DDS) or a crystal oscillator, is received atpre-amplifier 215 and conveyed to mixer 214. Mixer 214 modulates the RFsignal using the analog pulsing (modulating) signal and outputs a pulsedRF signal. The pulsed RF signal is filtered via filter 216, and thefiltered RF signal is amplified via AGC amplifier 218 to output anamplified pulsed RF signal. The level of attenuation is controlled by acontrolled feedback loop (i.e., including control block 224) 226,similar to as described above with reference to FIGS. 1A and 1B.

FIG. 2B shows an embodiment of an example RF generation system 250including an RF generator 252, according to various embodiments of thedisclosure. RF generation system 250 further includes a computer 254 andcommands 256, which may include a series (e.g., one or more) ofcommands. For example, commands 256 may include commands for describinga pulsed waveform having specific pulse characteristics using a syntaxrecognized by RF generator 252.

RF generator 252 includes an interface 258, a digital shaper 260, a D/Aconverter 262, a pre-amplifier 265, an AGC amplifier 268, a filter 266,a power amplifier 270, a power sensor 272, and a control unit 274. Insome embodiments, RF generator 252 includes a feedback loop 276.Further, AGC amplifier 268 and/or power amplifier 270 may be part of anamplification stage.

Commands 256 may be provided to RF generator 252 via interface (e.g., aninterface similar to the interface described with reference to FIGS. 1Aand 1B) 258. Commands 256 may include power levels and time span foreach segment in the pulse span. Commands 256 are received at a digitalshaper 260, which is configured to interpret the commands to generate adigital representation of a single-period pulsed waveform and to stichthe single-period of the pulsed waveform into a continuous pulsedwaveform. Digital shaper 260 outputs a bit stream representative of thedigital pulsed waveform. D/A converter 262 generates an analog pulsedsignal in response to the digital continuous pulsed waveform receivedfrom digital shaper 260. The analog pulsed signal may be received atcontrol unit 274 and conveyed to AGC amplifier 268.

A RF signal (e.g., an RF carrier signal), generated via, for example, adirect digital synthesizer (DDS) or a crystal oscillator, is received atpre-amplifier 215 and conveyed to AGC amplifier 268. AGC amplifier 268modulates the RF signal using the analog pulsing (modulating) signal andoutputs a pulsed RF signal. The pulsed RF signal is filtered via filter266, and the filtered RF signal is amplified via power amplifier 270 tooutput an amplified pulsed RF signal. The level of attenuation iscontrolled by a controlled feedback loop (i.e., including control block224) 276, similar to as described above with reference to FIGS. 1A, 1B,and 2A.

In the embodiments of FIGS. 2A and 2B, a user may program RF generator202/252 to use a pulsing waveform having pulses of any shape viainterface 208/258 by using commands 206/256. It will be appreciated thatin the embodiments of FIG. 2A and 2B, a user does not require anexternal signal generator for any waveform used to pulse the RFgenerator.

As mentioned above, conventional RF generators known to the inventors ofthis disclosure use a pulsed signal that has two states: high (on) andlow (off). The pulsed/pulsing (modulating) signal is used to switch anRF signal on/off to generate an RF signal with the same pulsing patternas the pulsed/pulsing signal.

Some embodiments relate, generally, to a pulsed RF generator that mayreceive and use a pulse stream having a waveform with more than twosignal levels (i.e., more than just high and low). Such a pulsed signalis referred to herein as a “multi-step” pulsed signal. In someembodiments, the RF generator modulates the RF signal using themulti-step pulsed signal. It will be appreciated that any analogarbitrary waveform may be used with such embodiments of an RF generator.In some embodiments, the multi-step pulsed signal source is generated bysignal generation equipment external to the pulsed RF generator.

FIG. 3A shows an embodiment of an example RF generation system 300including an RF generator 302, in accordance with various embodiments ofthe disclosure. RF generation system 300 further includes an analogsignal generator 305 coupled to RF generator 302. RF generator 302includes a mixer 314 and a pre-amplifier 315. RF generator 302 furtherincludes a filter 316, an AGC amplifier 318, a power amplifier 320, apower sensor 322, and a control unit 324. In some embodiments, RFgenerator 302 includes feedback loop 326. Further, AGC amplifier 318and/or power amplifier 320 may be part of an amplification stage.

In the embodiment of FIG. 3A, RF generator 302 may be configured togenerate a pulsed RF signal in response to an analog multi-step and/orarbitrary pulsed signal. In a contemplated operation, an analog pulsedsignal (e.g., with a multi-step and/or an arbitrary waveform) is outputby analog signal generator 305 and received at mixer 314. Further, mixer314 receives a RF signal (e.g., generated via a direct digitalsynthesizer (DDS) or a crystal oscillator) via pre-amplifier 315, andgenerates a pulsed RF signal by modulating the RF signal using thepulsed analog signal as a modulating signal. The power level of thepulsed RF signal is regulated to the requested power set point at eachstep or each level of the pulsed RF envelope. The set point iscontrolled by controlled feedback loop (i.e., including control unit324) 326, similar to as described above with reference to FIGS. 1A, 1B,2A and 2B.

FIG. 3B shows an embodiment of another example RF generation system 350including an RF generator 352, in accordance with various embodiments ofthe disclosure. RF generation system 350 further includes an analogsignal generator 355 coupled to RF generator 352. RF generator 352includes an analog-to-digital (A/D) converter 357, a pre-amplifier 365,and a filter 366. RF generator 352 further includes an AGC amplifier368, a power amplifier 370, a power sensor 372, and control unit 374. Insome embodiments, RF generator 352 includes a feedback loop 376.Further, AGC amplifier 368 and/or power amplifier 370 may be part of anamplification stage.

In a contemplated operation, a modulating signal with arbitrary waveformis output by an analog signal generator 355 and received at A/Dconverter 357. In response to the modulating signal, A/D converter 357generates a digital signal that is received at control unit 374 andconveyed to AGC amplifier 368. AGC amplifier 368 receives a RF signal(e.g., generated via a direct digital synthesizer (DDS) or a crystaloscillator) via pre-amplifier 365 and filter 366, and generates a pulsedRF signal by modulating the RF signal using the digital signal as amodulating signal. The power level of the pulsed RF signal is regulatedto the requested power set point at each step or each level of thepulsed RF envelope. The set point is controlled by controlled feedbackloop (i.e., including control unit 374) 376, similar to as describedabove with reference to FIGS. 1A, 1B, 2A, 2B, and 3A.

It will be appreciated that in the embodiment illustrated in FIG. 3A, anarbitrary analog signal is used by an RF generator to modulate an RFcarrier to create an RF envelope that follows the arbitrary waveformenvelope. Further, it will be appreciated that for embodiments disclosedwith reference to FIGS. 1A, 1B, 2A, and 2B, external analog signalgeneration equipment may not be required to generate a modulating signalhaving a desired pulsed waveform. Also, it will be appreciated that forembodiments disclosed with reference to FIGS. 1A-3B, the RF generationsystems enable modulating an RF signal with an arbitrary waveform and toaccurately control the RF Peak Envelope Power (PEP).

Some embodiments relate to RF plasma generation, and more specifically,RF plasma excitation using a pulsed/pulsing RF signal generatedaccording to one or more disclosed embodiments. FIG. 4 is a blockdiagram of an example semiconductor manufacturing system 400 configuredfor using RF plasma excitation. System 400 includes an RF generator 402(e.g., RF generator 102 of FIG. 1A, RF generator 152 of FIG. 1B, RFgenerator 202 of FIG. 2A, RF generator 252 of FIG. 2B, RF generator 302of FIG. 3A, or RF generator 352 of FIG. 3B) configured to provide apulsed RF signal to a plasma chamber 405 via an RF matching network 407(e.g., to match the output impedance of the pulsed, or CW, RF generatorto the impedance of the plasma chamber constituting the load to the RFgenerator and to maximize power transfer) for plasma excitation therein.

FIG. 5 shows an embodiment including a simplified example of an RFplasma generator 500, which may be used for deposition and/or etching(e.g., in a semiconductor manufacturing process that uses pulsed RFsignals generated in accordance with disclosed embodiments). RF plasmagenerator 500 includes an RF generator 502, a RF matching network 507,and an apparatus 530, which may include, for example, a deposition/etchapparatus. For example, RF generator 502 may include RF generator 102 ofFIG. 1A, RF generator 152 of FIG. 1B, RF generator 202 of FIG. 2A, RFgenerator 252 of FIG. 2B, RF generator 302 of FIG. 3A, RF generator 352of FIG. 3B, or RF generator 402 of FIG. 4 . Apparatus 530 includes anumber of showerheads/electrodes 532 and a chuck 534. RF plasmagenerator 500 further includes a gas source (e.g., a reactant gassource) 540, a RF bias generator 542, a RF matching network 544, and anexhaust line 546.

FIGS. 6A-6F show non-limiting example waveforms comprising pulse trainshaving various non-limiting examples of pulse waveforms. The waveform inFIG. 6A, designated “single step,” shows an example pulse train whereeach pulse exhibits one amplitude during its duty cycle. The waveform inFIG. 6B, designated “two step,” shows an example pulse train where apulse exhibits two distinct amplitudes during its duty cycle. Thewaveform in FIG. 6C, designated “three step,” shows an example pulsewhere the pulse exhibits three distinct amplitudes during its dutycycle. The waveform in FIG. 6D, designated “N step,” shows an examplepulse where the pulse may exhibit N distinct amplitudes during its dutycycle (here it exhibits three amplitudes but it could exhibit, forexample 2, 4, 1, 5, 20 without limitation). The waveform in FIG. 6E,designated “pulsing steps up and down” shows an example pulse where thepulse exhibits N distinct amplitudes during the first half of its dutycycle (the step up half of the duty cycle) and N distinct amplitudesduring the second half of its duty cycle (the step down half of the dutycycle). The waveform in FIG. 6F, designated “arbitrary waveform” showsan example of a user defined pulse train where the pulses each have adifferent arbitrary shape. More specifically, this example shows abalanced (equal portions of the duty cycle are assigned to each step)two-step pulse followed by a single step pulse with a ramp down, andthen an imbalanced (unequal portions of the duty cycle are assigned toeach step) two-step pulse. The arbitrary waveform that modulates the RFsignal can also be of random nature, not necessary an N-step pulse, orramped up or down.

FIG. 7 is a flowchart of an example method 700 of generating a pulsed RFsignal, in accordance with various embodiments of the disclosure. Method700 may be arranged in accordance with at least one embodiment describedin the present disclosure. Method 700 may be performed, in someembodiments, by a device or system, such as RF generation system 100 ofFIG. 1A, RF generation system 150 of FIG. 1B, RF generation system 200of FIG. 2A, RF generation system 250 of FIG. 2B, RF generation system300 of FIG. 3A, RF generation system 350 of FIG. 3B, semiconductormanufacturing system 400 of FIG. 4 , RF plasma generator 500 of FIG. 5 ,or another device or system. Although illustrated as discrete blocks,various blocks may be divided into additional blocks, combined intofewer blocks, or eliminated, depending on the desired implementation.

Method 700 may begin at block 702, wherein an analog signal may begenerated based on one or more commands, and method 700 may proceed toblock 704. For example, the one or more commands (e.g., commands 206 ofFIG. 2A or commands 256 of FIG. 2B) may define a pulsed waveform. For,example, analog signal (e.g., the arbitrary pulsed analog signal) may begenerated via a digital shaper, a D/A converter, a combination thereof,or another suitable device.

At block 704, a RF carrier may be modulated using the analog signal, andmethod 700 may proceed to block 706. For example, the RF carrier may bemodulated via a mixer (e.g., mixer 114 of FIG. 2A) or an AGC amplifier(e.g., AGC amplifier 168 of FIG. 2B).

At block 706, a pulsed RF signal obtained responsive to the modulation(i.e., at block 702) may be amplified. For example, the pulsed RF signalmay be amplified via power amplifier 120 of FIG. 2A or power amplifier170 FIG. 2B.

Modifications, additions, or omissions may be made to method 700 withoutdeparting from the scope of the present disclosure. For example, theoperations of method 700 may be implemented in differing order.Furthermore, the outlined operations and actions are only provided asexamples, and some of the operations and actions may be optional,combined into fewer operations and actions, or expanded into additionaloperations and actions without detracting from the essence of thedisclosed embodiment. For example, method 700 may include one or moreacts wherein a digital continuous pulsed waveform is generated based ona waveform file. Further, method 700 may include one or more actswherein the pulsed analog signal is generated based on the digitalcontinuous pulsed waveform. Further, method 700 may include one or moreacts wherein the waveform file comprising an arbitrary pulse waveform isreceived via an interface. Method 700 may also include one or more actswherein samples of the amplified pulsed RF signal are sensed and anerror signal is generated based on a comparison of samples of theamplified pulsed RF signal to pre-defined set points. Further, method700 may include an act wherein a power level of the pulsed RF signal isattenuated in response to the error signal.

While the present disclosure has been described herein with respect tocertain illustrated embodiments, those of ordinary skill in the art willrecognize and appreciate that the present invention is not so limited.Rather, many additions, deletions, and modifications to the illustratedand described embodiments may be made without departing from the scopeof the invention as hereinafter claimed along with their legalequivalents. In addition, features from one embodiment may be combinedwith features of another embodiment while still being encompassed withinthe scope of the invention as contemplated by the inventor.

What is claimed is:
 1. An apparatus, comprising: a signal generator togenerate a pulsed radio frequency (RF) signal at least partiallyresponsive to a digital pulsed waveform defined by one or more commands;an amplification stage to amplify the pulsed RF signal; and a feedbackcontrol loop coupled to the amplification stage to regulate a powerlevel of respective steps of the pulsed RF signal.
 2. The apparatus ofclaim 1, wherein the digital pulsed waveform comprises one or morepulses that respectively exhibit a multi-step waveform or and anarbitrary waveform.
 3. The apparatus of claim 1, comprising: anattenuator coupled between the signal generator and the amplificationstage to attenuate a power level of the pulsed RF signal in response toan error signal generated via the feedback control loop.
 4. Theapparatus of claim 3, wherein the attenuator comprises an automatic gaincontrol (AGC) amplifier coupled between the signal generator and a poweramplifier of the amplification stage.
 5. The apparatus of claim 1,wherein the feedback control loop comprises a digitalproportional-integral-derivative (PID) controller or an analog PIDcontroller.
 6. The apparatus of claim 1, comprising a power sensor togenerate samples of the amplified pulsed RF signal.
 7. The apparatus ofclaim 1, wherein the signal generator comprises: an analog signalgenerator to generate a pulsed analog signal responsive to the digitalpulsed waveform defined by one or more commands; and a modulator togenerate the pulsed radio frequency (RF) signal by modulating an RFcarrier utilizing a modulating signal comprising the pulsed analogsignal.
 8. The apparatus of claim 7, wherein the modulator comprises: amixer to receive the RF carrier and the modulating signal comprising thepulsed analog signal.
 9. The apparatus of claim 7, wherein the analogsignal generator comprises: a digital shaper to generate a digitalcontinuous pulsed waveform at least partially responsive to the digitalpulsed waveform defined by one or more commands; and a digital-to-analog(D/A) converter to generate the pulsed analog signal at least partiallyresponsive to the digital continuous pulsed waveform.
 10. The apparatusof claim 7, wherein the modulator comprises: an automatic gain control(AGC) amplifier to receive the RF carrier and the modulating signalcomprising the pulsed analog signal.
 11. A method, comprising:generating a pulsed radio frequency (RF) signal at least partiallyresponsive to one or more commands defining a digital pulsed waveform;amplifying the pulsed RF signal; and regulating a power level ofrespective steps of the pulsed RF signal via a feedback control loop.12. The method of claim 11, comprising: receiving the one or morecommands defining the digital pulsed waveform via a communicationinterface.
 13. The method of claim 12, wherein the communicationinterface is coupled to a computer.
 14. The method of claim 11, whereinthe regulating the power level of respective steps of the pulsed RFsignal via the feedback control loop comprises: generating samples ofthe amplified pulsed RF signal; generating an error signal based on acomparison of samples of the amplified pulsed RF signal to pre-definedset points; and attenuating the pulsed RF signal responsive to the errorsignal.
 15. The method of claim 11, wherein generating the pulsed radiofrequency (RF) signal comprises: generating a pulsed analog signal atleast partially responsive to the one or more commands defining thedigital pulsed waveform; and modulating an RF carrier utilizing amodulating signal comprising the pulsed analog signal.
 16. The method ofclaim 15, wherein generating the pulsed analog signal comprises:generating a digital continuous pulsed waveform at least partiallyresponsive to the one or more commands defining the digital pulsedwaveform; and converting the digital continuous pulsed waveform into thepulsed analog signal.